1. Technical Field
The present invention relates to a porous glass base material sintering method and sintering apparatus.
2. Related Art
A method for a transparent glass by sintering suppressing an outer diameter variation of a porous glass base material has been proposed (for example, refer to Patent Document 2).    Patent Document 1: Japanese Patent Application Publication No. 2003-081642    Patent Document 2: Japanese Patent Application Publication No. 2005-008452